Lung separation with one-lung ventilation is a medical and anesthetic technique that may be employed during certain surgical operations that involve thoracotomy, thoracoscopy or video-assisted thoracoscopic surgery, as well as for medical conditions such as pulmonary alveolar protienosis. One-lung ventilation may be achieved by blocking and isolating one side of the lungs, while selectively ventilating either the ipsilateral or contralateral side of the lungs. Such a procedure may permit a collapsed lung to facilitate the surgical operation and, more importantly, prevent contamination to the contralateral healthy lung from blood or pus materials. In one such method, one-lung ventilation may be achieved by including a single-lumen endobronchial tube, a double lumen endotracheal tube (or double lumen tube, DLT), and a bronchial blocker in conjunction with an endotracheal tube.
The conventional single-lumen endobronchial tube may be placed or configured in one of the main bronchi to block and ventilate the ipsilateral healthy or non-operative lung. This tube may be simple in structure and may be easy to place but may have disadvantages. Some disadvantages may include: 1) because the right main bronchus is short and close to the tracheal bifurcation, when a single-lumen endobronchial tube is placed in the right side, its cuff may block the takeoff of the right upper lobe bronchus, restricting ventilation only to the right middle and lower lobes, a condition usually unsuitable for effective ventilation and oxygenation; 2) this type of tube may not deflate nor provide access to the contralateral diseased or operative lung; and 3) if inflation or ventilation of the contralateral operative lung is needed for surgical or anesthetic reasons during lung operation, the tube may be retracted to the trachea, thereby compromising the isolation and leading to contamination. As a result, the conventional single-lumen endobronchial tube has generally become obsolete in practice, with the exception of occasional use in small children when no other methods can be used.
The conventional double-lumen (endotracheal or endobronchial) tube (DLT) is essentially an endobronchial tube bound to an endotracheal tube. When in place, the endobronchial tube fits in the main bronchus, isolating and ventilating one side of the lungs, while the endotracheal part resides in the trachea and provides access and ventilation to the other side. Therefore, when placed correctly, the DLT provides isolation of, as well as access and ventilation to, both sides of the lungs. This is especially advantageous in certain clinical conditions such as severe pulmonary protienosis requiring lavage, unilateral pulmonary abscess or hemorrhage, or bronchial fistula in which separation of lungs are absolutely necessary. Two major drawbacks DLTs are related to the bulkiness of the construction of the DLT. The drawbacks can include: (1) severe injury to airway may occur, and (2) it can be a challenge to place a DLT n difficult airway scenarios such as difficult laryngoscopy or intubation, lesions and abnormal anatomy of the trachea, or when nasal intubation may be required. Furthermore, if postoperative intubation is indicated, the DLT must be removed and the patient must be reintubated with a regular endotracheal tube after the surgery when airway conditions are generally compromised due to the intubation.
To overcome the aforementioned disadvantages of the DLT, bronchial blockers were introduced for use with the regular endotracheal tubes. These bronchial blockers can be placed either alongside or inside the endotracheal tube, and include the original Uninvent tube and subsequent Uniblocker (Fuji), Arndt, Cohen, Coopdech endobronchial blockers, EZ-blocker, and other balloon-tipped catheters. While each of the foregoing structures has unique properties, all may include a distal cuff to block a main or lobar bronchus of the ipsilateral operative lung, and most have a small lumen (<2 mm) for evacuation and collapse of, as well as for continuous positive airway pressure (CPAP) application to, the operative lung. The bronchial blocker technique offers several benefits over the DLT. The endotracheal tube associated with this technique may be generally easy to place and may be successful in difficult airways requiring techniques not suitable for the DLT. During a combined thoracotomy and laparotomy procedure, the blocker may be removed after finishing the thoracotomy, leaving only the endotracheal tube for the abdominal procedure. Similarly, the endotracheal tube may be left for postoperative ventilation if required, thereby avoiding postoperative tracheal tube exchange.
Although the comparative efficacy and complication rates of the DLT versus the bronchial blockers are debatable, one significant shortcoming associated with a conventional bronchial blocker is that the evacuation of secretions, blood or pus from the operative or diseased lung is neither effective nor reliable through its small lumen (2 mm or less), which clogs easily and becomes inoperable, and even leads to reinflation of the operative lung. In addition, placing a large endotracheal tube for housing a conventional bronchial blocker is still challenging if possible in patients with difficult intubation. Finally, and more importantly, conventional bronchial blockers typically do not provide working access or ventilation to the blocked lung, and, therefore, cannot generally be used for bronchial lavage, pulmonary hemorrhage, bronchopleural fistula or bronchial surgery during which access to the diseased lung is critical.
Laryngeal mask airway and other supraglottic airway devices may serve as alternatives to mask ventilation and tracheal intubation, or as rescue airways and conduits for tracheal intubation. When placed properly, the laryngeal mask may cover the larynx with its tip resting on the upper end of the esophagus and its airway lumen facing the glottic opening. Generally, the laryngeal mask may create a seal around the glottis, forming a functional connection between its airway lumen and the trachea. The second generation of laryngeal mask airways includes a gastric access channel that may passively drain or actively evacuate gastric contents, and may vent air leakage from the airway, allowing for higher intra-airway pressure during positive ventilation. Practitioners have often relied on the laryngeal mask airway and other similar devices for airway management in a variety of surgeries including functional craniotomies, bronchoscopy, laparoscopy procedures; however, their application in thoracic surgery has been limited, and involves the laryngeal mask in combination with a bronchial blocker. The combination of a laryngeal mask and a bronchial blocker offers a new alternative method of one-lung ventilation, particularly in difficult airway; however, it cannot avoid the limitations of the bronchial blockers, namely limited efficacy and lack of access to the diseased lung.